1. Field of the Invention
The present invention relates to a unidirectional ratchet wrench integrally formed with a control plate by a sheet metal manufacturing process.
2. Description of the Related Art
With reference to FIG. 2 for a conventional ratchet wrench as disclosed in U.S. Pat. No. 7,100,477, the conventional ratchet wrench has the following shortcomings:
1. In the prior art as shown in FIG. 2, a metal sheet 21 is stamped into arc iron plates, and an inverted L-shaped bent rod 22 is manufactured and welded at an appropriate position, and a protruding rod 23 is welded from the bend rod 22, and a press plate 24 is welded from another end of the metal sheet 21, and thus the metal sheet 21 has to go through a complicated manufacturing procedure.
2. In the prior art as shown in FIG. 1, a front edge of the metal sheet 21 is coupled to ratchet teeth 31 of a ratchet 30, such that when the ratchet 30 is rotated in 360 degrees, the tip of each ratchet tooth 31 rubs with the front edge of the metal sheet 21, and the ratchet teeth 31 are worn out slightly. After the ratchet 30 has been worn, a unidirectional ratchet block 25 of the ratchet wrench is no longer engaged with the ratchet 30 properly, and the rotation torque becomes too weak. If an adhesive is used for fixing the metal sheet 21 into an arc embedded groove 15, then the metal sheet 21 will not rub with the ratchet teeth 31, but the foregoing structure fixed with the metal sheet 21 involves an additional manufacturing process.
3. In the prior art as shown in FIG. 4, the unidirectional ratchet block 25 has a hole 28 for containing an elastic element 29, but the unidirectional ratchet block 25 formed by casting powder cannot form the hole 28. The hole 28 is drilled, and such manufacture incurs a higher manufacturing cost.
Another conventional ratchet wrench as disclosed in U.S. Pat. No. 6,862,955 has the following shortcomings:
1. In the prior art as shown in FIG. 3, the positioning element 30 is in the same shape of the first containing groove 21 and the second containing groove 22 of the wrench body 20, and thus the positioning element 30 requires a higher cost.
2. In the prior art as shown in FIG. 5, the spring 34 is installed in the positioning portion 33 and abutted against a lateral side and a top surface 42 of a latch block 40, and thus the spring 34 is rubbed with the latch block 40 to cause a damage easily.
3. The positioning element 30 and the ratchet 50 are contained in the wrench body 20, and thus it is necessary to add the thickness of the positioning element 30 to the first containing groove 21, and thus the wrench body 20 is thicker than a general wrench.